US3679538A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Novel open-celled microporous film
Assignee: Celanese Corp
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Filing: 1970-10-28
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Granted: 1972-07-25
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Expires: 1990-10-28
Abstract
Abstract OPEN-CELLED MICROPOROUS POLMER FILMS CHARACTERIZED BY HAVING A REDUCED BULK DENSITY AS COMPARED TO THE BULK DENSITY OF THE CORRESPONDING POLYMER FILMS HAVING NO OPEN-CELLED STRUCTURE, A CRYSTALLINITY OF ABOVE ABOUT 30 PERCENT, A PORE SIZE OF LESS THAN 5000 ANGSTROMS AND A NITROGEN FLUX OF GREATER THAN 35.4, ARE PREPARED BY THE CONSECUTIVE STEPS OF COLD STRETCHING, HOT STRETCHING AND HEAT SETTING A NON-POROUS, CRYSTALLINE, ELASTIC FILM.
Inventors
- 👤 Melvin L Druin
- 👤 John T Loft
- 👤 Steven G Plovan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:34
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/04; B29C55/06; B29C55/065; B29C55/023; B29L; B29L2023/00; B29L2023/001; Y; Y10; Y10S; Y10S264/00; Y10S264/08; Y10S264/13; Y10S264/16; Y10S264/47; Y10S521/00; Y10S521/918; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249978; Y10T428/249979; Y10T428/26; Y10T428/268; Y10T428/31504; Y10T428/31855; Y10T428/31938
Claims Analysis
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References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |